Bernie Sanders fiercely condemned President Donald Trump on Monday following reports that the president shared highly classified information with Russian officials during their White House visit last week.

The Vermont senator called Trump’s actions “reckless and dangerous” in a statement released Monday evening.

“President Trump, in a reckless and dangerous manner, has revealed highly classified information to the Russians at a meeting in the Oval Office, information that could expose extremely important sources and methods of intelligence gathering in the fight against ISIS,” Sanders said in the statement.

“Protecting our national security is one of the most important tasks a president has, and Trump is failing at it.”

Sanders then referenced Trump’s surprise firing of FBI Director James Comey last week, a move Trump said he made in part because of Comey’s handling of an investigation into Trump’s ties to Russia. After the dismissal, Trump issued a cryptic threat to Comey in which he mentioned the possible existence of recordings of their conversations, prompting calls for Trump to release them.

“All of this makes it vitally important that Trump make public any recordings he has of conversations in the Oval Office,” Sanders said in his statement.

Numerous Senate Democrats have joined Sanders in condemning Trump on Monday.

Details of Trump’s disclosure were first reported by The Washington Post and subsequently confirmed by Reuters and The New York Times.